October 01, 2009

Lancet Researchers Say Aging Process is Modifiable

Physorg reports that the Lancet in an article to be published Friday in the medical journal Lancet (prestigious medical journal), the researchers write that the process of aging may be "modifiable." The Lancet is saying there is no fixed ceiling on human longevity.

If the pace of increase in life expectancy in developed countries over the past two centuries continues through the 21st century, most babies born since 2000 in France, Germany, Italy, the UK, the USA, Canada, Japan, and other countries with long life expectancies will celebrate their 100th birthdays. Although trends differ between countries, populations of nearly all such countries are ageing as a result of low fertility, low immigration, and long lives. A key question is: are increases in life expectancy accompanied by a concurrent postponement of functional limitations and disability? The answer is still open, but research suggests that ageing processes are modifiable and that people are living longer without severe disability.

"The linear increase in record life expectancy for more than 165 years does not suggest a looming limit to human lifespan. If life expectancy were approaching a limit, some deceleration of progress would probably occur. Continued progress in the longest living populations suggests that we are not close to a limit, and further rise in life expectancy seems likely," Kaare Christensen, of the Danish Aging Research Center at the University of Southern Denmark, and colleagues wrote.

Most babies born in rich countries this century will eventually make it to their 100th birthday, new research says. Danish experts say that since the 20th century, people in developed countries are living about three decades longer than in the past. Surprisingly, the trend shows little sign of slowing down.

James Vaupel of the Max Planck Institute in Germany and colleagues in Denmark examined studies published globally in 2004-2005 on numerous issues related to aging. They found life expectancy is increasing steadily in most countries, even beyond the limits of what scientists first thought possible. In Japan, for instance, which has the world's longest life expectancy, more than half of the country's 80-year-old women are expected to live to 90.

"Improvements in health care are leading to ever slowing rates of aging, challenging the idea that there is a fixed ceiling to human longevity," said David Gems, an aging expert at University College London. Gems was not connected to the research, and is studying drugs that can lengthen the life span of mice, which may one day have applications for people.

"Laboratory studies of mice, including our own, demonstrate that if you slow aging even just a little, it has a strong protective effect," he said. "A pill that slowed aging could provide protection against the whole gamut of aging-related diseases."

back in June, I pointed out a longevity mutation that only extends healthy life span in male mice. By way of a bookend to that discovery, here is a mutation that extends healthy life span by 20% or so in female mice only.

Researchers have identified a genetic tweak that can slow aging in mice:

Caloric restriction has long been known to extend lifespan and reduce the incidence of age-related diseases in a wide variety of organisms, from yeast and roundworms to rodents and primates. Exactly how a nutritionally complete but radically restricted diet achieves these benefits has remained unclear. But recently several studies have offered evidence that a particular signaling pathway, involving a protein called target of rapamycin (TOR), may play a pivotal role. This pathway acts as a sort of food sensor, helping to regulate the body's metabolic response to nutrient availability. Withers and colleagues noticed that young mice with a disabled version of the protein S6 kinase 1 (S6K1), which is directly activated by TOR, bore strong resemblance to calorie-restricted mice: they were leaner and had greater insulin sensitivity than normal mice.

The more recent results in S6K1 knockout mice are one small part of the flurry of research into the biochemistry of calorie restriction. Scientists are racing to explore pathways and mechanisms gene by gene and protein by protein, seeking the best place to intervene using designed drugs. The goal is to capture all the benefits of calorie restriction, or even do better, whilst minimizing or eliminating unwanted side-effects. Give it another ten years and the new scientific industry of metabolic manipulation will rival that of stem cell research, I'd wager. It certainly seems set for that sort of growth, starting from calorie restriction biochemistry and working its way outward.